The present invention relates to a control device for a static var compensator (SVC) and a control method thereof, and in particular, to a control device for a SVC which is applied to high voltage direct current (HVDC) power transmission.
The HVDC power transmission refers to a power transmission method in which a power transmitter converts AC power generated by a power generator into DC power and transmits the DC power, and a power receiver converts the DC power back into AC power and supplies the AC power to customers.
The SVC is a device for compensating for reactive power which is lost during electric power transmission and distribution to enhance stability of power transmission and also is a system for removing limitations, such as power loss in an AC system, by applying power conversion technology of a thyristor of an existing current-type HVDC system.
The SVC is used as core facilities of power companies, steel companies, or flexible AC transmission systems (FACTS). The FACTS supplies power stably even when the generation quantity of renewable energy, such as wind energy or solar energy, is rapidly changed, thus minimizing power transmission loss, efficiently using existing power networks, and also maintaining system stability.
A valve destruction interface of the SVC generates a final firing signal by adding a firing signal transmitted by an upper controller to a databack signal received from a gate unit and transmits the final firing signal to the gate unit. However, there may be much difficulty in system configuration since the types and number of databack signals significantly increase depending on various conditions which may occur during valve management. Also, when an error occurs due to unstable environments, considerable time and manpower are required to deal with and process the error.
For example, an existing system for compensating for reactive power receives pieces of data from lower systems and checks an error by calculating the pieces of data. Specifically, the existing system determines an error in a thyristor, an error in conducting information, an error in gamma operation information, and an error in break-over diode (BOD) information, based on the pieces of received data, and when it is determined that there is no error with respect to all the information, informs that there is no error in data information by outputting a firing signal.
In particular, the primary purpose of the existing system is to check and control a state of a valve from a time point at which the firing signal is started.
Therefore, there is much difficulty in system configuration since the types and number of databack signals significantly increase depending on various conditions which may occur during management.
Also, when an error occurs due to unstable environments, considerable time and manpower are required to deal with and process the error. In particular, since a period is set to 16.67 ms with respect to the firing signal, there are limitations in simultaneously controlling gate units in the entire system. Furthermore, there is a problem in which, although a control operation related to a corresponding line during one period is completed, a subsequent sequence can proceed only when a control operation related to another line is completed.
Also, there is complexity in signal transmission to transmit a signal to a valve through a control and protection (C&P) of the upper controller.